This section is intended to introduce the reader to various aspects of the art that may be related to various aspects of the present invention. The following discussion is intended to provide information to facilitate a better understanding of the present invention. Accordingly, it should be understood that statements in the following discussion are to be read in this light, and not as admissions of prior art.
In today's CDMA architecture, Base Stations (BTS), Base Station Controllers (BSCs), and their related signaling links, are associated with a single Mobile Switching Center (MSC). MSC pooling has been proposed in the 3GPP2 standards to allow BSCs and their related BTSs to connect to multiple MSCs, in case one or more of the MSCs has a critical failure or is isolated from the network.
The related 3GPP2 MSC Pooling standards (S.R0136 and A.S0018) introduce the concept of a Serving Node Selection Function (SNSF). The SNSF logically sits between the MSC and BSC, and routes the associated signaling between the appropriate pooled MSC and the BSC. Once an MSC has a critical failure or is otherwise isolated, the SNSF selects another functional MSC from the MSC pool to serve the mobiles from the failed MSC.
The S.R0136 standard mentions that “When one MSC or MSCe in an MSC Pool breaks down, the interruption time for users being registered in this node should be minimized. In other words, another MSC or MSCe within the MSC Pool shall take over the communication services (e.g., call origination, call delivery, etc.) from this node as quickly as possible.” The standard does not give any guidance around shortening any the interruption time for any of these services, only that the interruption is resolved as quickly as possible.
Mobile call originations are not seriously impacted, as those calls will perform an implicit registration with the Home Location Register (HLR) and then route as per normal. Call delivery (mobile termination) interruptions could be longer, as some operators only have their mobiles register with the network once per day to reduce HLR traffic. A shorter call delivery interruption time would be useful.